/*
 *  Copyright 2013 National Institute of Advanced Industrial Science and Technology
 *  
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *  
 *      http://www.apache.org/licenses/LICENSE-2.0
 *  
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.sss.util;

public class WaitCallback<T> implements CallbackInterface<T> {
  private int n;
  private T result = null;

  public WaitCallback() {
    this(1);
  }

  public WaitCallback(int n) {
    assert n > 0;
    this.n = n;
  }

  @Override
  public synchronized void callback(T arg) {
    if (--n == 0) {
      this.result = arg;
      this.notifyAll();
    }
  }

  public synchronized T waitAndGet() throws InterruptedException {
    while (n > 0) {
      this.wait();
    }
    return result;
  }
}
